Plaque bacteria colonize the tooth and bring about an influx of bacterial toxins, enzymes, and metabolites which may prompt localized development of an inflammation of the gingival tissues, gingivitis. The local host tissue inflammatory response to the bacterial pathogens' challenge includes infiltration of a variety of cell types (e.g. polymorphonuclear leukocyte, lymphocytes, plasma cells, macrophages) that have various roles in counteracting the tissue insult presented by the plaque pathogens and their products. In many individuals, the continuing presence of plaque pathogens and the associated inflammatory response leads to periodontitis, which involves the progressive destruction of the connective tissue attachment for teeth and of alveolar bone supporting the teeth.
The periodontal attachment apparatus is comprised of the cementum, periodontal ligament and its component fibers connecting the tooth to the socket of alveolar bone. When healthy, the periodontal attachment occurs just apically of the junction between the tooth enamel and the cementum of the root. Clinically, loss of periodontal attachment at a specific site on a tooth is determined with a calibrated periodontal probe by measuring the distance between the junction of the root cementum and enamel and the level at the base of the periodontal pocket where a periodontal probe meets resistance to mechanical probing. If there is attachment loss, there likely is also a periodontal pocket. If loss continues due to periodontal pathogen colonization, alveolar bone loss may result. This tissue destruction may be retarded but is not reversed by traditional therapeutic interventions.
Within populations of patients having periodontitis, the rate of disease progression varies widely; additionally, within individual patients, the disease progresses at markedly different rates among different sites in the mouth. Individual teeth and their respective root surfaces in the mouth are each sites where periodontitis may occur with varying degrees of severity. Presently, it is believed that disease may progress in either a chronic linear fashion over time or in an episodic manner with bursts of disease activity separated by periods of remission. In either event, it is clear that when a patient population is followed over time there are marked differences in the incidence of clinically demonstrable disease progression among patients and among sites within each patient's mouth.
The prospective detection of patients and sites at increased risk of disease progression is very important to effective dental treatment. Detection of an increased risk for disease progression enables the early identification of those patients and those sites that most need therapeutic or preventative treatments to halt the tissue destructive phase of the disease process.
Presently, there are no effective means to evaluate a patient's risk, or a site's risk, of experiencing continued attachment loss, i.e. active disease. Clinical measures of disease progression provide a measure of prior disease activity but do not provide a means of differentiating among sites or patients with high or low levels of risk of future disease activity.
The host immune response to plaque pathogens includes producing both molecules that protect gingival tissues from the destructive effects of invading bacteria and also molecules produced during the host response that can destroy periodontal tissues. For example, lymphocytes produce antibodies against plaque pathogens that neutralize bacteria and their toxic products. Meanwhile, inflammatory cells can release various hydrolytic enzymes which can cleave and degrade protein and polysaccharides of key periodontal tissue structural components.
The antibodies produced against periodontal pathogens bind to the pathogens or their products forming antigen-antibody complexes. These antigen-antibody complexes result in the neutralization and agglutination of plaque pathogens and their products. The complexes also facilitate the phagocytosis, killing, and degradation of the pathogens and their products by the Polymorphonuclear leukocytes (PMNs). However, some of these antigen-antibody complexes can prompt secondary inflammatory responses because of their ability to activate the complement system, which is a cascade of proteolytic enzymes capable of activating various inflammatory mechanisms.
Betaglucuronidase (BG), which is a hydrolytic enzyme and an enzyme marker for PMN activation, is involved in the acid degradation of mucopolysaccharides/proteoglycans. Indeed, increased gingival crevicular fluid (GCF) levels of BG have been reported in periodontitis patients with an increased incidence of active periodontitis. Thus, it appears that with active periodontitis there is an increased engagement of periodontal pathogens by PMNs within or near the gingival tissues.
While bacterial pathogens are necessary for the development of gingivitis and periodontitis, measuring the presence or absence of specific bacterial pathogens themselves is not a sufficient or effective means of predicting the likelihood of experiencing active disease. Consequently, effort to develop a means of predicting future disease activity has been focused on the association of various molecules found in the gingival crevicular fluid exuded due to the host factor response during the course of the disease (see, Lamster, I. B., et al, Enzyme Activity in Crevicular Fluid for Detection and Prediction of Clinical Attachment Loss in Patients with Chronic Adult Peridontitis, J. Periodontol., 59, pp. 516-523, (1988) (hereinafter Lamster), and Palcanis, K. G., et al, Elastase as an Indicator of Periodontal Disease Progression, J. Periodontol., 63, pp. 237-242, (1992) (hereinafter Palcanis)).
The GCF comprises the same molecules as those produced by the host cells in the gingival tissues or gingival crevice. The GCF, therefore, provides a profile of those host molecules present in the gingival tissues and may be used to indicate the reactions and responses taking place therein. Current research tends to focus on measuring the presence of host molecules that might be associated with the destruction of gingival tissues. Thus, levels of various inflammatory mediators (e.g. Prostaglandins E2), putative tissue destructive/hydrolytic enzymes (e.g. Betaglucuronidase and elastase), and enzyme markers for cell death (e.g. aspartate aminotransferase) found in gingival crevicular fluid have been evaluated for their association with patients or sites having an increased risk of active disease as compared to those in which no measurable clinical change in periodontal attachment is detected (see, Lamster and Palcanis). The correlation between the presence of these molecules and future disease activity has not proved to be strong enough to provide a generally acceptable and reliable method of predicting risk of disease activity.
An object of the subject invention is to provide a method for detecting an increased risk for progression of periodontal disease in humans and lower animals.
A further object of the subject invention is to provide diagnostic kits useful for detecting and evaluating the risk of disease progression for patients or particular periodontal sites in humans or lower animals.